The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present disclosure but provided by the present disclosure. Some such contributions of the present disclosure may be specifically pointed out below, while other such contributions of the present disclosure will be apparent from their context.
With the evolvement of mobile communication systems, various wireless communication techniques have been standardized and released, such as Global System for Mobile Communications (“GSM”), Enhanced Data rates for GSM Evolution (“EDGE”), Universal Mobile Telecommunications System (“UMTS”), High Speed Link Packet Access (“HSPA”), Long Term Evolution (“LTE”), Long Term Evolution Advanced (“LTE-A”) and etc. Each of these standards has a particular signal specification, modulation types, transmission power requirements, and dedicated operating frequency bands, which are different from one geographic area to another across the globe. For instance, according to the existing wireless communication standards and frequency planning, there are a couple of frequency bands for mobile devices to operate on, for example, 850, 900, 1800, and 1900 MHz bands in 2G GSM standard, 850, 900, 1800, 1900 and 2100 MHz bands in 3G standards, 700, 800, 850, 900, 1700, 1800, 1900, 2100, and 2600 MHz bands in 3.9G Frequency Division Duplex (“FDD”)-LTE standards, and 2300, 2600 and 2700 MHz bands in 3.9G time division duplex (“TDD”)-LTE standards.
In order to provide wireless communication users with global roaming functionality under different frequency bands as exampled above, mobile devices that support various communication standards to co-exist and interoperability between multiple frequency bands, which are generally referred to as Multi-Mode Multi-Band (“MMMB”) devices, are emerging. Such an MMMB-enabled mobile device generally includes an MMMB RF PA circuitry, in which a separated low voltage and impedance RF PA is arranged for each operating frequency range. For example, for dual frequency band operations, the existing MMMB RF PA requires two separated low voltage and impedance PAs. Therefore, in order to support multiple frequency band operations, there would be correspondingly multiple separated low voltage and impedance PAs. However, it would be hard to dispose such number of separated low voltage and impedance PAs in a single mobile device, which inevitably increases the size, cost, and complexity of the mobile device. The same may hold true for signal amplifications that are carried out at a base station, which may be also referred to as a Node B, an evolved Node B (“eNB”) and etc in different wireless communication systems.
Therefore, there is a need for more powerful and efficient power amplifiers that are capable of operating over broader frequency ranges.